Before her daughter, Felicity Jackson, was diagnosed with Tourette syndrome, Felicity was called a freak and stared at by other pupils, and even teased by her teachers. ''She was really distressed. She couldn't face going to school,'' Ms Row said.

Tourette syndrome causes tics, involuntary movements and sounds, most commonly developing between the ages of five and seven. Felicity, 13, was diagnosed when her tics suddenly worsened a couple of years ago.

A talented dancer, she wished the tics would go away. ''They bothered me quite a lot. I noticed people were looking at me, and I just wanted it to stop,'' she said.

Ms Row visited her class and explained the rare and puzzling condition to students. They no longer stare or make comments.

NSW researchers are developing a program to help retrain the brains of children with Tourette syndrome, at the same time as identifying the unique genetic basis of the disorder.

Valsa Eapen, a researcher at the University of NSW and the Ingham Institute, said cognitive behavioural therapy could help override the tic urge.

People with Tourette syndrome seemed to have abnormalities in sensory ''gateways'' in the brain, she said. ''It's like a gate that holds back things for us normally, like the urge to scratch an itch or sneeze,'' she said.

By teaching the children to recognise urges and do opposite movements, tic severity can be reduced, she will tell the Australasian Society for Psychophysiology conference at the University of NSW this weekend.

Professor Eapen has also outlined for the first time the genetic chain of events that leads to the condition. Her research, published in the journal Translational Psychiatry, identified five genes that must be disrupted for it to develop. Some of those genes have also been linked to other developmental conditions such as attention-deficit hyperactivity disorder, obsessive compulsive disorder and autism.

''Unravelling the overlap between Tourette syndrome and the frequently co-occurring developmental and behavioural problems holds the key to better understanding of the biological basis of the disorder,'' she said.

The genetic chain helps explain why many children with developmental conditions share common symptoms - they may have some but not all the genes disrupted.

Professor Eapen said many people believed the urge to swear, rather than physical tics, was the most common feature of Tourette syndrome. ''The swearing occurs only in about one-third of cases, but for the majority that is not the case,'' she said.

Until recently it was thought the syndrome affected one in 1000 children but emerging research puts the figure closer to one in 100.